Video encoder with feedback control

摘要

A video signal encoder (10') operable for distinguishing between errors resulting from a change in a video signal input (at 16) to the encoder and errors resulting from ineffective quantization includes a quantized section (21) and an unquantized section (46), with each section having a separate image predictor (42,56). A switch mechanism (S1,S2) selectively provides each image predictor with a corresponding signal having a portion containing video data derived from a prior frame for use in predicting an image represented on a subsequent video frame. The signals are also provided to an image analysis unit (44') for measuring motion of the image and for adjusting a quantization step size of a quantizer (24) when quantization errors are detected.